Transformation of ice in aqueous KCl solution to a high-pressure, low-temperature phase

The changes in in situ Raman spectra of ice in aqueous KCl solution have been measured as a function of pressure at liquid nitrogen temperature (77 K). The ice that is formed abruptly transforms to a crystalline phase at ∼800 MPa. It has a spectrum close to that of ice VII′ to which high density amorphous (hda) ice transforms at about 4 GPa. This behavior contrasts with that of the ice in aqueous LiCl solution, which transforms to an amorphous phase at ∼500 MPa, as in the case of pressure-induced amorphization of ice Ih to hda.